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Fix mistakes (#86)

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ivanpanch
2025-08-22 09:32:30 +02:00
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parent 5326b49475
commit 46ee1c3528
2 changed files with 5 additions and 5 deletions
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doc/lexical_cast.qbk
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@@ -203,7 +203,7 @@ Read a good C++ book, study `std::sentry` and [@boost:libs/io/doc/ios_state.html
[pre
]
* [*Question:] Why `std::cout << boost::lexical_cast<unsigned int>("-1");` does not throw, but outputs 4294967295?
* [*Question:] Why does `std::cout << boost::lexical_cast<unsigned int>("-1");` not throw, but outputs 4294967295?
* [*Answer:] `boost::lexical_cast` has the behavior of `std::stringstream`, which uses `num_get` functions of
`std::locale` to convert numbers. If we look at the Programming languages — C++, we'll see, that `num_get` uses
the rules of `scanf` for conversions. And in the C99 standard for unsigned input value minus sign is optional, so
@@ -212,7 +212,7 @@ if a negative number is read, no errors will arise and the result will be the tw
[pre
]
* [*Question:] Why `boost::lexical_cast<int>(L'A');` outputs 65 and `boost::lexical_cast<wchar_t>(L"65");` does not throw?
* [*Question:] Why does `boost::lexical_cast<int>(L'A');` output 65 and `boost::lexical_cast<wchar_t>(L"65");` not throw?
* [*Answer:] If you are using an old version of Visual Studio or compile code with /Zc:wchar_t- flag,
`boost::lexical_cast` sees single `wchar_t` character as `unsigned short`. It is not a `boost::lexical_cast` mistake, but a
limitation of compiler options that you use.
@@ -220,7 +220,7 @@ limitation of compiler options that you use.
[pre
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* [*Question:] Why `boost::lexical_cast<double>("-1.#IND");` throws `boost::bad_lexical_cast`?
* [*Question:] Why does `boost::lexical_cast<double>("-1.#IND");` throw `boost::bad_lexical_cast`?
* [*Answer:] `"-1.#IND"` is a compiler extension, that violates standard. You shall input `"-nan"`, `"nan"`, `"inf"`
, `"-inf"` (case insensitive) strings to get NaN and Inf values. `boost::lexical_cast<string>` outputs `"-nan"`, `"nan"`,
`"inf"`, `"-inf"` strings, when has NaN or Inf input values.
@@ -229,7 +229,7 @@ limitation of compiler options that you use.
]
* [*Question:] What is the fastest way to convert a non zero terminated string or a substring using `boost::lexical_cast`?
* [*Answer:] Use `boost::iterator_range` for conversion or `lexical_cast` overload with two parameters. For example, if you whant to convert to `int` two characters from a string `str`, you shall write `lexical_cast<int>(make_iterator_range(str.data(), str.data() + 2));` or `lexical_cast<int>(str.data(), 2);`.
* [*Answer:] Use `boost::iterator_range` for conversion or `lexical_cast` overload with two parameters. For example, if you want to convert to `int` two characters from a string `str`, you shall write `lexical_cast<int>(make_iterator_range(str.data(), str.data() + 2));` or `lexical_cast<int>(str.data(), 2);`.
[endsect]
example/generic_stringize.cpp
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@@ -14,7 +14,7 @@
In this example we'll make a `stringize` method that accepts a sequence, converts
each element of the sequence into string and appends that string to the result.
Example is based on the example from the [@http://www.packtpub.com/boost-cplusplus-application-development-cookbook/book Boost C++ Application Development Cookbook]
Example is based on the example from the Boost C++ Application Development Cookbook
by Antony Polukhin, ISBN 9781849514880. Russian translation: [@https://dmkpress.com/catalog/computer/programming/c/978-5-97060-868-5/ ISBN: 9785970608685].
Step 1: Making a functor that converts any type to a string and remembers result: